In the manufacture of tissue roll products, such as bath tissue and paper towels, uncreped throughdried products have gained wide acceptance with consumers. These products are characterized in part by their high bulk, three-dimensional texture and resilience. In the case of paper towels, exceptional bulk is provided by contoured throughdrying fabrics that impart high and wide wales or ridges that run in the machine direction of the product. In the case of bath tissues, the same technology is utilized, but the throughdrying fabrics employed impart a smaller scale topography to the product. While it would be desirable to use the same throughdrying fabric for both towels and bath tissue from the standpoint of manufacturing efficiency, using the more highly contoured towel throughdrying fabric for making bath tissue causes two significant problems.
First, the consumer preferred fiber basis weights and tensile strengths associated with bath tissue products are, for the most part, less than the basis weights and tensile strengths preferred for paper towels. Given the high contour of the fabrics used for paper towel products, the lower basis weights and tensile strengths used for bath tissue products cannot accommodate the substantial z-directional displacement of the web during wet molding and drying. As a result, the final product contains an unacceptable number of pinholes caused by the web being stretched to conform to the topography of the throughdrying fabric.
In addition, because bath tissue is desirably calendered to control caliper and soften and smoothen the product, the dried web undergoes widening as it is “extruded” from the calender nip. This web widening is amplified as the bulk of the tissue base sheet is increased. This extrusion phenomenon creates inconsistencies during winding, which results in substantial waste and delay.
Therefore there is a need for a method of making highly contoured uncreped throughdried paper towels and bath tissue on the same tissue machine using the same throughdrying fabric.